Improve the -j option; set default value to 1

README.md

@@ -78,6 +78,7 @@ Options:
  - `--max-age` - Considers only rows younger than specified. See `--min-age`.
  - `--bisection-factor` - Segments per iteration. When set to 2, it performs binary search.
  - `--bisection-threshold` - Minimal bisection threshold. i.e. maximum size of pages to diff locally.
+ - `-j` or `--threads` - Number of worker threads to use per database. Default=1.
 
 
 # How does it work?

data_diff/__main__.py

@@ -44,7 +44,12 @@
 @click.option("-v", "--verbose", is_flag=True, help="Print extra info")
 @click.option("-i", "--interactive", is_flag=True, help="Confirm queries, implies --debug")
 @click.option(
- "-j", "--threads", default=None, help="Number of threads to use. 1 means no threading. Auto if not specified."
+ "-j",
+ "--threads",
+ default="1",
+ help="Number of worker threads to use per database. Default=1. "
+ "A higher number will increase performance, but take more capacity from your database. "
+ "'serial' guarantees a single-threaded execution of the algorithm (useful for debugging).",
 )
 def main(
  db1_uri,
@@ -76,11 +81,20 @@ def main(
  elif verbose:
  logging.basicConfig(level=logging.INFO, format=LOG_FORMAT, datefmt=DATE_FORMAT)
 
+ threaded = True
  if threads is not None:
- threads = int(threads)
- if threads < 1:
- logging.error("Error: threads must be >= 1")
- return
+ if threads.lower() == "serial":
+ threaded = False
+ threads = 1
+ else:
+ try:
+ threads = int(threads)
+ except ValueError:
+ logger.error("Error: threads must be a number, 'auto', or 'serial'.")
+ return
+ if threads < 1:
+ logging.error("Error: threads must be >= 1")
+ return
 
  db1 = connect_to_uri(db1_uri, threads)
  db2 = connect_to_uri(db2_uri, threads)
@@ -106,8 +120,8 @@ def main(
  bisection_factor=bisection_factor,
  bisection_threshold=bisection_threshold,
  debug=debug,
- threaded=threads != 1,
- max_threadpool_size=threads,
+ threaded=threaded,
+ max_threadpool_size=threads and threads * 2,
  )
  diff_iter = differ.diff_tables(table1, table2)